{% if username != null %}
<html lang="zh-CN">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
    <meta name="description" content="">
    <meta name="author" content="">
    <title>登录跳转</title>
    <meta http-equiv="refresh" content="1;url=/admin/index/"> 
  </head>
  <body>
    <p>登录成功，正在跳转...</p>
  </body>
</html>
{% else %}
<!DOCTYPE html>
 <html lang="zh-CN">
   <head>
     <meta charset="utf-8">
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ -->
     <meta name="description" content="">
     <meta name="author" content="">
     <link rel="icon" href="../../favicon.ico">
     <title>Signin Template for Bootstrap</title>
     <!-- Bootstrap core CSS -->
     <link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
 
     <!-- Custom styles for this template -->
     <link href="/static/css/signin.css" rel="stylesheet">
   </head>
 
   <body>
 
     <div class="container">
       <form class="form-signin" action="/admin/login" method="POST">
         <h2 class="form-signin-heading">Please sign in</h2>
         <label for="inputEmail" class="sr-only">Email address</label>
         <input type="text" name="username" class="form-control" placeholder="Username" required autofocus>
         <label for="inputPassword" class="sr-only">Password</label>
         <input type="password" name="passwd" class="form-control" placeholder="Password" required>
         <input class="btn btn-lg btn-primary btn-block" type="submit" value="Sign in"/>
       </form>
     </div>
   </body>
 </html>
 {% endif %}